Hob grinder



C. G. OLSON HOBGRINDER Nov. 7, 1933.

Filed July 9, 1931 4 Sheets-Sheet 1 s uw wm o 4M o m QM' owowd MT5 S1 m EN QN mms nwww. SN Sw HTW S Nov. 7, 1933. c, G. oLsoN Hoa GRINDER Filed July 9, 1931 4 Sheets-Sheet 2 aan jo i; 396s 74 J am l 60 ez M 76- 7a ao a6 .-5 5E l ...HHH T- V100 Nov. 7, 1933.

C. G. OLSON HOB GRINDER Filed July 9, 1931 4 Sheets-Sheet 5 lz/erz/Ztb/rf Car G. 006011] @I @M4 77M@ Nov. 7, 1933. c. G. oLsoN 1,933,872

HOB GRINDER Filed July 9, 1931 4 Sheets-Sheet 4 Patented Nov. 7, 1933 PATENT OFFICE non Gnmnna Carl G. Olson, Chicago, Ill.,

Tool Works, Chicago, Ill.,

Illinois assignor to Illinois a corporation o! Application Jnly 9, 1931. Serial No. 549,679

'l Claims.

My invention relates generally to grinding machines and particularly to machines for grinding the relieved surfaces on the teeth of rotary cutters,

such as hobs and the like.

One of the objects of my present invention is to provide a grinding machine of improved practical construction, whereby the relieved surfaces of hob teeth and the like may ground, and to this end I propose to provide a grinder arrangement which will enable both sides of the hob teeth to be ground from the same side of the hob by a pair of grinder wheels, which are shiftable into and out of operative association with the hob teeth.

More specifically, my invention contemplates the provision of a grinding machine, in which a pair of 'grinder wheels are so arranged on one side of the supported work piece that one wheel may be employed to grind one side of the hob teeth, and upon the completion of its grinding action, the other grinder may be shifted into position for grinding the other side of said teeth.

Another object of my invention is to provide a grinding machine, as above set forth, which is equipped with a rotary work spindle having a mounting, this mounting serving to rigidly secure said spindle against lateral deflection.

Still another object of my invention is to provide, in combination with the elements as above set forth, an improved compensating or sine bar mechanism for imparting axial movement to the work spindle and thereby alter the axial movement which is imparted to the hob by a master lead screw.

A further object is to provide improved means for dressing a pair of conical grinder wheels.

Another object of my invention is to provide a unitary means or cam mechanism forshifting the grinder wheel in accordance with the relief on the hob teeth, said cam mechanism being designed to effect they automatic positioning of the grinder wheel clear of the supported hob when the machine is operated in a reverse direction.

In addition to the above mentioned advantageous structural features, my invention contemplates the provision ofa hob grinding machine, as above set forth, having an improved universal joint connection between the master lead screw and the main drive shaft of the machine, whereby to prevent said screw from being subjected to severe stresses.

It is also an object of my invention to provide a hob grinding machine, as above set forth, which is automatically reversible upon the completion of its grinding stroke.

be emciently The foregoing and numerous other objects and advantages will be more apparent from the following' detailed description when considered in connection with the accompanying drawings, wherein- Figure 1 is a front elevational view of a hob grinding machine, which is constructed in accordance with the teachings of my present invention;

Figure 2 is an enlarged transverse sectional view of the machine taken substantially along the line 2-2 of Figure 4; l

Figure 3 is an enlarged fragmentary View of the left end of the machine shown in Figure 1, to more clearly disclose the gear driving mechanism;

Figure 4 is an enlarged fragmentary plan view of the right end of the machine in Figure 1, disclosing a grinder wheel in operative association with the work piece;

Figure 5 is a detail sectional view of the grinder unit and parts associated therewith, said view 'l being taken substantially along the line 5-5 of Figure 4',

Figure 6 discloses the grinder unit of Figure 4 in its shifted position whereby the other grinder wheel is positioned in operative association with 30 the opposite side of the hob teeth;

Figure 'I is an enlarged transverse sectional view taken substantially along the line '1 -'1 of Figure 1;

Figure 8 is a plan tially along the line 8-8 of Figure 7; and

Figure 9 is a perspective exploded view of the various elements which constitute the compensating or sine bar mechanism shown in Figures 7 and 8.

Referringnow to the drawings more in detail wherein like numerals have been employed to designate similar parts through the various 'iigures, it will be seen that for the purpose of illustrating one practical embodiment of my invention, I have shown the same in association with a hob grinding machine. This machine includes a base or bed 10, the left end of which, Figure 1, carries upright supports 12 and 14. These 'supports provide a mounting at their upper ends for a drive spindle 16, which carries a large gear 18. This gear 18 meshes with an elongated pinion 20 suitably mounted within the supports 12 and 14, the power is delivered to this pinion from a suitable drive mechanism, which I have indicated generally by the numeral 22 in Fig- -ure 1. This drive mechanism may be of any conventional design; and hence a detailed description thereof is not essential for a clear understanding of the present invention. It will suffice sectional view taken substan- 35 tosaythatthisdrive mechanism22includesa suitable prime mover or electric motor 24, which is adapted to deliver power through suitable gearing to a shaft 26. The direction of rotation of this'shaft may be controlled by a conventional clutch mechanism 28, the functioning of which is controlled by a lever arm 30. When the clutch occupies its middle position shown in Figure l, no power is delivered to the shaft 26, and when said clutch mechanism is shifted to one side, said shaft will rotate in a given direction, and when shifted to the opposite sid said shaft will be driven in an opposite direction. Thus the direction of rotation of the pinion is dependent upon the positioning of the clutch 28.

Coupled with the drive spindle 16 through the agency of a universal Joint 32, is a master lead screw 34. By employing the universal joint 32, I am able to eliminate the stresses and strains otherwise experienced by the lead screw when it is formed integral or pomtively conected as a unit with' the drive spindle 16. 'lhe lead screw 34 rotates within a suitable nut 36, and the outer end of the screw provides a work supporting spindle 38. This spindle 38 is adapted to receive a work piece, such as a hob and said hob is clamped in position upon the work piece by a nut 'Ihe extremity of the spindle 38 is reduced andmountedwithinabearing 44. Thisbearing is provided at the upper end of an upright support or bracket 46, which, in turn, is bolted or otherwise secin'ed to a slide 48. which is horizontally shiftable in a direction parallel to the axis of the spindle 38. From the foregoing it will be apparent that, when rotatestodrive thelargegear 18,thescrew 34 will operate within the companion'nut 36 so as to impart longitudinal' movement to the hob 40. This linear travel in one direction is imparted to the hob 40 during with the hob teeth of one of a pair of grinder wheels and 50a, Figure 4.

These grinder wheels 50 and 50a form/parts ofagrinderunitorheadwhichlhavedesignated generally by the numeral 52. This grinder unit 52 includes a pair of grinder spindles 54 and 54a,

which are disposedv at substantially right angles and are rotatable within carriers or holders 56 and 56a respectively, which are formed integral withamainbaseplate. Theplatc58is adapted to be shifted within the plane thereof upon .a pivotal support o`r block 60. 'Ihe block 60 issuppolrtedbyaslide 62, and a clamplngpin 64, which is pivoted within the slide 62, receives a clamping nut 68, which serves to retain the plate 58 in its pivotal relation with respect to theblock60."lhe plate58isadaptedtobe shifted between two positions, one position shown inFigure4andtheotherpositionshowninFigure 6. In Figure 4 the grinder wheel/50 is positioned in operative assoclationewith one side of thehobteeth,andinFigure6thiswheelisout of contact with the hob teeth, and the grinder wheel`50a is operatively associated with the opposite side of the hob teeth. 'Ihe grinder unit 52isadaptedtobesecuredineitherof thesepositions through the agency of a retractable latch member 68, which is adapted tobe received by notches formed along an arcuate portion, of the plate 58. A coiled springa72 serves to continuously urge the latch member 68 toward-they plate 58, 'andln order to releaseuthe latch member from fthe plate, it is only n to exert an outward pull on a knob 'I4 provided at the outer end ofthe latch member. Attention is directed the operative association` to the factthat the block 60 not only serves as a pivotal support for the grinder unit, but also positions said unit in accordance with the thread angle of the hob 40. This may be more clearly observed from the structure shown in Figure 5. To change the angular disposition of the grinder unit to accord with another thread angle of the hob, it is only necessary to insert another block having a corresponding angular disposition.

The slide 62 which supports the grinder unit, is mounted upon a slide 76. This slide 76 is adjustable longitudinally of the work axis by means of a screw 78, and the slide 62 is adjustable transversely of the work axis by means of a screw 80. [A slide 82 which supports the slide 76, is shiftable in afdirection transverse to the work axis upon a bed or frame 84. 'Ihe shifting of the slide 82 is occasioned in response to the actuation by a cam 86 keyed to a shaft 88, Figure 2. This cam engages the lower portion of a finger 90 which is pivoted to the underside of the slide 62. An adjustable fulcrum block 92 is positioned intermediate the ends of the nger 90, and said nger pivots on said fulcrum to eil'ect the transverse shifting of the slide 82. Vertical adjustment of the fulcrum block 92 may be made by turning a shaft 94 which is connected by bevel gears to a screw 96 passing through the fulcrum block. Variation in the position of the fulcrum block will effect a variationinl the degree of travel imparted to the slide 82. A coiled spring 98 interposed between one end of the slide 82 and a fixed projection 100 of the frame 84 serves to continuously urge said slide to the right, Figure 2, thereby maintaining engagement between the finger 90 and the surface of the cam 86. The cam 86 causes the slide 82 and th'e parts supported thereby to be shifted toward the work piece in accordance with the relief on the teeth of the hob 40. It will be seen that when the :linger 90 is positioned within a low section 86a of the cam 86, the operative grinder wheel will be positioned out of contact with the hob so that, whenv said hob is moved axially. the grinder wheel will clear the periphery thereof. Thus when' it is desired to reverse the axial travel of the hob after a grinding operation has been completed, the cam is automatically shifted so as to position the linger 90 in the low surface portion 86a of the cam, there by permitting the hob to be shifted in a reverse direction without engaging the grinder wheel.

'I'he cam shaft 88 is coupled with a drive shaft 102 through the agency of a clutch mechanim 104, Figure 1. This mechanism 104 includes a clutch member 106 and a clutch member d108. The clutch member 108 shaft 102, and a coiled spring 110 serves torontinuously urge the clutch member 108 into operative association with the companion member' 106. When rotation is imparted to the clutch member 108 in a clockwise direction. as viewed from the left of Figure l. positive rotation is imparted to the shaft 88 and cam 86, and this rotation takes place during the grinding of the relieved surfaces on the hc' teeth. Upon the completion of the grinding stroke, reverse rotation is imparted to the shaft 102, namely, in a counterclockwise direction, as viewed from the left of Figure' 1, and during this rotation the clutch member 108 impositively drives the member 106 so as to move the low surface portion 86a of the cam into operative association with the lower end ofthe actuating finger 90. After the cam has been moved to this position the clutch lai) is coupled with the lso vdriving pinion 20.

reverse. shifting of the weighted arm 122.

member 108 clicks past the companion memvbei' 106.

Vfrom and are adapted to be adjustably secured to the rod 112. The lower extremities of these arms. 118 and -120 are provided with .pins 1l8a and 12Qa respectively, which are adapted to engage a lever 122, the upper end of which carries a weight 124. This lever is adapted, when shifted to the vright. to engage -a bolt 126 carried by a shifter bar 128, and thereby urge said bar to theright, Figure 1. Likewise, when the lever 122 is shifted to the left, it is adapted to engage a bolt 130 so as to movethe ,bar 128 tothe left. This bar 128 is connected at its left extremity to the upper end of the lever arm 30, and at its right end to the pivoted control lever 132. The

shifter rod 112 is moved inresponse to the lon-v plane. said weight will cause the arm 122 to be suddenly shifted, thereby eifectlng'the sudden actuation of the clutchmechanism 28. Thus when one of the grinder wheels completes its cutting action, the Y pin 118a will cause the weighted arm 122 to be shifted to the right, thereby" actuating the clutch mechanism 28 so as lto effect reverse Yrotation of the elongated Likewise, when the work piece or hob reaches this vextreme position'to the left, Figure 1. the pin 120a will.cause the .My invention is in no sense limited to the particular type\of vreversing mechanism disclosed herein, but contemplates the use of other control devices without departing from the spirit land scope thereof. v

Attention'is now directed to the compensating or sine bar mechanism, which I have designated generally by the numeral 236. 'I'his mechanism includes the slide 48 which is shiftable in a direction parallel to the work axis upon a guide 238 provided along the upper surface of the machine bed 10. One extremity of this slide' 48 carries the upright spindle support 46,-as clearly shown in Figure l.l The opposite end of the slide 48 supports a plate 240 having arcuate slots 242 provided in each end 'thereof'. which slots are concentric, with a pin 244. This pin-244 extends within the medial portion of an adjustable sine bar 246 provided with a groove 248. A bridge frameA 250 is secured .tothe bed l0 and provides a slidable support for aplate 252,'which is shiftable in a direction transverse to the movement of the slide 48. Depending from the center'of the'plate 252 and positioned within the .groove 248 is a pin 254. Secured tothe upper surface of the plate 252 is a pair of plate sections'258 and 258, which arespaced to provide a groove 260, which is angularly disposed with respect to the direction of movement of the plate 252. Extendlng'within the groove 260 and carried on the underside ofna slide 262 is a pin 264. slide 262 supports an upright frame `member 266, which carries thenut 36 in which the master lead screw 34 operates. Toi'zontinually urge the slide 262- to the left, Figure 1, I employ a coiled spring 268,

which is interposed between an extension 262a on the slide and the outer surface of the bridge frame 250.

The operation of the mechanism .just described is as follows: The rotation of the master screw 34 in a given direction within the nut 36 causesl the hob 40 to be longitudinally shifted to the right. This causes the slide 48, which is coupledv with the work spindle, to be also 'shifted to the right. Figure 1. The bar- 246 also moves to the right with the slide 48, and this causes the plate 252 to be shifted transversely within the bridge frame 250. The direction in which the plate 252 shifts will be dependent upon the angular disposition of the bar 246. Consider, for example, that the\bar 246 is positioned as shown in Figures 7 to 9 inclusive. As the.bar 246 is shifted to the right, the plate 252and its associated. plate sections 256 and 258 will be urged rearwardly, as viewed in Figure 8, or to the right. as viewed in Figure 7. Shifting these parts in this direction causes the slide 262, which carries the filler pin 264, to be shifted to the left, as viewed in Figure 1. In other words, by having lthe sine bar mechanism set up, las disclosed in the drawings, a movement is superimposed upon the screw 36, which causes the work .piece or hob 40 to shift at a rate which is less than the rate at which it would shift if the lead screw were employed as the sole actuating mechanism. It

will be clear that this sine bar mechanism 236 serves as a compensating means, which enables a hob having a lead differing from that 'of the lead screw, to'be shifted longitudinally at a rate which corresponds wi"h the lead of the hob. If the lead of the hob is greater than the lead of the 11()A master screw, the sine bar 246 may be shifted to 'its opposite angular position and thereby superimpose an increased rate of travel -to the master screw and work spindle. The coiled spring 268 serves to continually urge the pin or roller 264 against the surfaceof'the plafe 258,-and in order to maintain engagement between thev pin 254 and a wall ofthe groove 248 in the sine bar, I provide a pair of Y oppositely disposed coiled springs 270 and 272 which are housed within-the plate 252.

viewed ln Figure '1, is the actuating wall of the 125 bar 246, the plunger 2741s moved into the plate 252 so as to increase the compressing action of Y the spring 270, and the plunger 276 is urged out-. wardlyto decrease Ithe compressing force of the spring 272. Under reverse conditions namely, 1

may be made across the distance indicated at A, 135

Figure 8, which extends between a1 pin 278 carried at the lef: end of the bar 246 and an abutment member 280 secured in a fixed position upon the plate 240. In this manner very accurate readings may be made for properly setting lthe 11g sine bar 246. The angular setting of the sine bar may also be read by gaduations 28'2 posivtioned along the end arcuate surface of the `plate 24o, Figure 9. N

It will be noted thatfthe universal joint or coapling 32 includes a member 284, Figure 1, whichv n is pivoted about a vertical axis o'f acollai 28g. supported at the left end of the master screw 34. This member 284 is also pivoted about a horizontal axis to a collar 288 lcarried at the right end of the drive spindle 16. In this manner any lateral stresses to which the drive spindle may in the event that the screw and drive spindle were integral.

The grinder wheels 50 and 50a may be contemporaneously Adressed by means of a dressing or truing m indicated generally by the numeral 290, Figures 2 and 4.l This mechanism includes a vertically disposed guide 292 supported by the grinder unit 52, and adjustable within the guide 292 isa slide 294. .Extending thrQUh the slide 294 is a pin 296, one en d of whichsupports a hand lever 2.98, and the other end-a thumb nut 300.v The lower end of the hand lever 298 carries a dressing element 302, suchasadiamond, anditwillbeseenthat, when'the hand lever is -pivoted about the axis of the pin 296,. the dressing element will be moved across the conical surface of the grinder wheels 50 and 50a. The slide 294 is secured in various positions of vertical adjustment within the guide 292 by means of a set screw 304, Figure 4." The truing element or diamond 302 moves in an'arcuate path which lies in the piane of the work faces of the grinder wheels. Movvertically adjusting the position of the truingdef.

vice. the proper surface contour may be imparted to said wheels.

From the foregoing it will be apparent that my invention contemplates the provision of a grinding machine o f improved practical construction, whereby hobs and cutters of like nature may be ground with extreme accuracy. By having the grinder wheels disposed in the manner described as to enable the successive grinding of both surfaces of the hob teeth by simply 'shifting one wheel out of contact and the other wheel into contact with thework, the speed of grinding'the hob is materially increased. The mountingof the master screw and work spindle as described materially contributes to the rigid- .ity of the machine structure. The sine bar Havingthusldescribed my invention, what I.

claim asnew and desire to Patentis:

1. A hob grinding machine including a rotary hob spindle, a pairof grinders positimed on the same side of said spindle, one grinderbeingadaptedtogrindthereliefonone aideofthehobteethandtheotherad'aptedto secure b y Letters `grindthereiidontbeoppomtesideofsaidteetm a support for said grinders whereby one may be maintained out of ent with the work while the other grinder is functionally operative, means for effecting relative movement between the hob and grinders longitudinailyof the hob spindle, means for imparting relative transverse movemmtbetweenthehobandgrindersinac- AT5 .mm'withtherdief-entbehobteethganda hob supporting spindle, a grinder support, a.

grinder on said support for grinding the relieved surfaces of the teeth of a hob supported by said spindle. means for supporting said spindle on opposite ends of the supported hob, asine bar mechanism for imparting relative movement be,-

tween the hob and the grinder longitudinally of said hob, and means for imparting relative transverse movement between the hob and .the grinder in accordance with the relief on the hob teeth.-

3. A hob grinding machine including a rotary hob supporting spindle, means coupled with said spindle at one end thereof for imparting rotation to said hob, a bearing means for the opposite end of said spindle, a grinder for grinding the relieved surfaces of a hob supported by said spindle,l a sine bar mechanism coupled with said bearing means for -impartingr` relative longitudinal niovement between the supported hob and said grinder, and means for imparting relative ltransverse movement between the hob and grinder in accordance withthereliefonthehobteeth.

4. A hob grinding machine including a rotary hob supporting spindle, a grinder for grinding the relieved surfaces of a1 hob supported by said spindle, driving means coupled with said spindle on one side of the supported hob, means forrotatabiy supporting said spindle on the opposite side of said hob, actuating means operable in response to the functioning of' said spindle, said actuating means including a' bar adapted to be positioned obliquely'with Arespect to the axis of said hob spindle and means coupling` said bar with the last mentioned spindle support and cooperating with v'said bar to effect relative longitudinal supported hob and 'sam is movement between a grinder, and means for ,imparting relative transilo verse movement between said hob and said grinder.

5. A hob grinding machine including a rotary hob supporting spindle, a grinder for grinding the relieved surfaces of a -hob supported by said,

spindle, driving means coupled with said spindle on one side of the supported-hob. means for rotatably supporting said spindle on' the opposite side of said hob, actuating means operable in response to the functioning of said spindle, said actuating means including an adjustable bar adapted to be positioned obliquely with respect to the axis of said hob spindle and means coupling said bar with the last mentioned spindle support and cooperating with said bar to eect relative longitudinal movement between a supported hob and said grinder, and means for imparting relative transverse movement between said hob and said grinder.

8. A hob grinding machine including a hob supporting spindle. a pain of conical grinder wheels positioned on one side thereof for grinding the relleved surfaces on said hob. a support for said grinder wheels, the axes of said wheels being disposed -at substantially vright angles, a dressing mechanism carried by said support, said mechanism including a shiftable member, a dressing element carried by said member. said member being adapted to shift across the conical surface of one i grinder wheel and thence acx'osstheconical surfact of the adjacent grinder wheel, whereby'to eii'ect the contemporaneous truing of said wheels,

means for effecting relative longitudinal movel able member, a dressing element carried by said member, said member being adapted to shift across the conical surface of one grinder wheel and thence across the conical surface of the adjacent grinder wheel, whereby to effect the contemporaneous truingof said wheels, means for effecting relative longitudinal movement between the hob and grinder wheels, andmeans for effecting relative transverse movement between said hob and grinder wheels.

CARL G. OLSON.

ist 

